This application claims the benefit under 35 U.S.C. xc2xa7119 of co-pending German patent application number 198 41 508.7 entitled xe2x80x9cVerfahren zur xc3x9cbergabe von einzelnen Packstxc3xccken von einer Abnahmestelle an eine Stapelbildungsstelle sowie Vorrichtung zur Durchfxc3xchrung des Verfahrensxe2x80x9d, filed on Sep. 14, 1998.
The present invention generally relates to a method of transferring packing units from a receiving station to a stack building station. The invention also relates to a transfer apparatus for transferring packing units in a plurality of rows and in a plurality of tracks.
The method and the apparatus may be especially used to convey packing units in the form of blisters being filled with tablets from a press at the end of a thermoforming machine as receiving station to a stack building station being arranged at the entrance of a cartoning machine.
A one track method and a corresponding one track apparatus are known from the German Patent Application No. DE 36 17 259 A1. The end of a first packing machine serves as receiving station, and the entrance of a second packing machine serves as stack building station. A conveying device including rotors is arranged between the two packing machines, the rotors including three or four arms being movable in a clocked manner. The arms include suction elements, gripping elements or the like, and they each take over one packing unit at the receiving station. They pass the packing unit to the other rotors until the packing unit is inserted into the stack unit of the second packing machine at the stack building station. The two packing machines work at the same cycle, so that both packing machines simutaneously fulfil one cycle no matter whether or not a packing unit of desired properties is passed on. The packing system includes a device with which it is possible to remove undesired packages and to insert a desired package in the stream of material in the empty space. For this reason, an extra supply unit is allocated to the last rotor of the conveying device. At the beginning of a working cycle, a plurality of packages of desired properties is inserted into the extra supply unit, and the packages are stored therein. The extra supply unit can be automatically filled up to a predetermined minimum number of packing units of desired properties. During the operation of the system, the extra supply unit is filled up as soon as the predetermined minimum number of packing units is not reached any more. Although the transfer apparatus has a one track design, a relatively great minimum number of packing units of desired properties have to be stored in the extra supply unit. Usually, the packing units of desired properties to be stored first in the extra supply unit remain stored until the end of the packing cycle. When the extra supply unit is being filled, the second packing machine keeps on processing in a clocked manner, so that gaps may occur at the stack building station of the second packing machine.
A method and an apparatus for transferring packing units in a plurality of rows and in a plurality of tracks are known from the Otto Haensel GmbH leaflet xe2x80x9cHigh-Performance Thermoforming Line CP-12 And P-4xe2x80x9d, printed May 1987. The receiving station, the conveying device and at least the stack building unit of the following machine have a two track design, so that under normal conditions two packing units run through the system side by side in a clocked manner, and two packing units simultaneously arrive at the stack building unit, and they are collected side by side. The number of packing units in the two stacks usually increases uniformly. In case of an empty space in the region of one of the two tracks, there is a cycle in which only one packing unit is passed on to the stack building unit. Consequently, the number of packing units in one of the stacks is increased by one, whereas the number of packing units in the other stack remains unchanged. It is especially undesired to achieve stacks of different heights since this does not allow for the desired clocked processing of the stacks in the following machine. With this known apparatus, it is possible to remove packing units of undesired properties. Nevertheless, the object to achieve stacks of packing units of same height at the stack building station cannot be attained. To solve this problem, it is known from the above mentioned leaflet to allocate one extra supply unit for each track to the rotor of the conveying device. The extra supply units may be prefilled with packing units of desired properties to later fill empty spaces. The packing units of desired properties to compensate empty spaces remain in the extra supply unit for a rather long period of time until an empty space occurs. Thus, during this long period of time in which the packing units are stored in the extra supply unit, the properties of the packing units may change with respect to the other packing units of desired properties being conveyed through the system. For example, the deflection of the packages may change or packing units coming from other producing processes may have other properties. Thus, it is difficult to insert die packing units of different properties into one single carton. A change of charges or a change of format also makes it difficult to combine the packing units of different properties in one stack. The extra supply units only fulfil their function if a predetermined number of stored packing units is located in the extra supply unit.
From the European Patent Application No. EP 0 806 361 A1 an apparatus for depositing pairs of packing units in a carton is known. The packing units, for example bags being filled with potato chips and being sealed, are produced in one track, and they are partitioned in an non-described fashion to two tracks by a conveying device. At the same time, packing units of undesired properties are determined and removed. Empty spaces in the two tracks are prevented. Packing units of undesired properties are not replaced by stored packing units, but following packing units of desired properties are inserted in the empty space of the packing unit of undesired properties. The packing units of desired properties in the two tracks are banked, and they are further conveyed when a certain number of packing units is present in front of the bank position. In this way, two packing units of desired properties are inserted in one single common carton.
Briefly described, the present invention provides a method of transferring packing units from a receiving station to a stack building station, the method including the steps of delivering the packing units to the receiving station in a plurality of rows and in a plurality of tracks, accepting the packing units in a plurality of rows and in a plurality of tracks at a transfer apparatus, removing all packing units of desired properties from a first row not only including packing units of desired properties, storing the at least one packing unit of desired properties; and positioning the at least one stored packing unit of desired properties in a row following to the first row, so that only rows of packing units of desired properties are collected at the stack building station.
The present invention is generally based on the idea to convey the packing units arriving at the receiving station in a plurality of tracks and in a plurality of rows further on to a transfer apparatus still in a plurality of rows and in a plurality of tracks. The packing units may be observed at the receiving station, or in the region where the packing units are conveyed through the transfer apparatus to detect an empty space. Such an empty space may either be an empty blister or a blister of other undesired properties. For example, the blister may not be completely filled with the material. In all these cases, it is about a packing unit of undesired properties that has already been removed, or that will be removed. It is clear that a packing unit of undesired properties has to be removed before it may reach the stack building station. Usually, if there is a packing unit of undesired properties in one track, there is going to be a packing unit of desired properties in the other track of the same row. The packing unit of desired properties is then stored or buffered in the conveying path of the transfer apparatus. When the storing location is empty, the packing unit of desired properties is stored for a relatively short limited period of time. If the storing location is already occupied by another packing unit of desired properties, the stored packing unit may be used to fill the empty space where the packing unit of undesired properties was formerly located. The stored packing unit is only used to fill an empty space if a complete row of packing units of desired properties is formed therewith. In this way, either completely filled rows of packing units of desired properties are collected at the stack building station, or an empty row of packing units arrive at the stack building station, i.e. the transfer apparatus effects an empty transport at that time. Consequently, it is ensured that uniformly and evenly growing stacks of packing units of desired properties are attained for further processing.
The present invention is applicable to all cases in which packing units arrive at the receiving station in a plurality of tracks and in a plurality of rows, wherein a theoretical line connecting a first packing unit of a first row and a first track and a second packing unit of a second row of the same first track extends parallel to the main direction of movement of the packing units. The invention can be easily understood in case it is applied to two tracks of packing units. Thus, two adjacent tracks are arranged to work in a clocked manner. Each row of packing units includes only two packing units, and there are only three different undesired statuses. As an unusual status, there is either an empty space in one row of packing units in the first track, in the second track or in both tracks. The fourth possible case, which is the normal and the desired case, two packing units of desired properties are arranged in the two adjacent tracks in one and the same row. In this fourth case, there is no problem to be solved. The two packing units of desired properties are conveyed parallel to one another by the transfer apparatus, and each of them arrives at a stack at the stack building station. In case there is an empty space in only one of the two tracks, it is requested whether or not the storing location of the storing station is occupied by a packing unit of desired properties. In case the location is already occupied, the stored packing unit of desired properties is fed into the conveying stream, so that a row consisting of two packing units of desired properties is attained, and it can be further processed. Therefore, the storing location may have to change its position from one track to the other track. If the storing location of the storing station is empty, the packing unit of desired properties of the row is collected in the storing location, and a completely empty row arrives at the transfer apparatus, the transfer apparatus carrying out an empty stroke with respect to the stack building station. In the third possible error situation, meaning a complete row of two packing units of undesired properties arriving, these two packing units are removed, and the transfer apparatus also carries out an empty stroke with respect to the stack building station. In this case, the storing station is not actuated, and it remains in position.
The method according to the present invention provides a number of advantages: Due to stacks having the same height building up, and the full height of the stacks being achieved at the same time, complete stacks are always attained at the stack building station. The stack filling process is completed at the same time for all stacks, so that it is especially easy to further process the stacks. The plurality of stacks can either be handled simultaneously, it may be arranged to form a row, or it may be processed in another way, for example, the stacks may be inserted into a carton. The method according to the present invention further eliminates a bottleneck limiting the capacity of the entire machine and the entire system, respectively. The method and the transfer apparatus may be used in a deep drawing packaging machine with which especially tablets are packaged, and blister packages are produced, filled, covered, punched, stapled and moved as a stack into a carton. It is clear that such a deep drawing package machine may include additional special steps which are not described herein since they are of no special interest to the present invention, and they are known to a person with skill in the art. The application of the new method has the effect that portions of the deep drawing package machine may run at a comparatively low speed, as it is desired or even required for a certain processing step. This is possible although the entire capacity of the system is great. An essential advantage of the novel method is that the packing units are only stored for a relatively short period of time, and that the number of stored packing units of desired properties is very low. In case of a two track design of the conveying system, the maximum number of packages to be stored at a time is one. Additionally, another package of desired properties is stored when the first stored package has been inserted into the conveying stream. Thus, the danger of negative shrinkage effects at a packing unit is prevented. It is further essential that each packing unit of desired properties is guided and held during the conveying motion through the transfer apparatus at each time. There is no position in which is packing unit of desired properties is subject to gravity only. This means that the conveying and working velocity may be increased, and that the packing units of desired properties are safely and securely conveyed. The method according to the present invention already provides advantages in case of a two track system. But it is also possible to apply the present invention to systems having more than two tracks.
In case of at least two empty spaces or at least two spaces not including packing units of desired properties in one of the tracks, the stored packing unit of desired properties is moved from the track including the first empty space in a direction transverse to the conveying direction of the packing units, so that it is moved to the other track, and it is inserted into the track including the second empty space to form a completely filled row. This is true in case that two empty spaces occur right beside one another, as well as in case completely filled rows are located between the two empty spaces in one common track. In these cases, it is necessary to realize a change of tracks with the stored packing unit of desired properties, since the packing unit is needed in the other track to form a complete row. This is immediately true for a two track process. In case there are more than two tracks, substeps have to be carried out. The kind of the substep to be carried out depends on whether an empty row or a complete row of packing units of desired properties is to be realized.
In case of a two track design and the receiving station receiving two tracks of packing units, only one packing unit of desired properties is stored for a limited of time, and it is immediately used to fill a following empty space and to build a complete row consisting of two packing units. Thus, the period of time in which a packing unit is stored only lasts until a following empty space occurs, no matter in which one of the two tracks. The storing location of the storing station only has two different conditions. A packing unit of desired properties is either located and stored in the storing location, or the storing location is empty. Such a storing location is substantially different from a supply or stock unit in which a majority of packing units of desired properties is stored, the packing units remaining in the stack unit for varying periods of time. According to the present invention, the period of time during which the packing units are located in the packing location is relatively short. It depends on how often empty spaces occur that have to be filled. For example, the novel method may be used with a two track operation in case only one of the tracks is filled with packing units of desired properties and the other track is completely empty. In this case, the storing station also works from cycle to cycle and a working cycle and an empty cycle occur alternatingly at the stack building station.
In case of an at least three track supply of packing units at the receiving station, one or more packing units of desired properties are to be stored. In case of occurring empty spaces, the packing unit of desired properties or the packing units of desired properties are either used to fill the empty space, and they are fed into the stream of material to form a complete row consisting of a plurality of packing units, or, in case it is not possible to complete the row, an empty row is formed, and the packing unit of desired properties or the packing units of desired properties are stored to be used later. In case of such a three track supply, the number and the position of possible empty spaces is increased. There is a total number of seven error situations depending on whether it is possible to achieve a complete row, or if an empty row has to be produced. There are different steps to be carried out. It is easy to understand that in case of a three track design and operation, there is a maximum of two packing units of desired properties to be stored at a time. It is generally true that the maximum number of packing units of desired properties to be stored is less than the number of tracks by one. The necessary change of tracks has to be chosen to enable each storing location to fulfil the change of tracks to reach each and every track.
The transfer apparatus generally including a conveying device and corresponding stations also provides the advantages which have been already described with respect to the novel method. There is an additional aspect of the storing station having a rather simple structure since the number of packing units of desired properties to be stored at a time is advantageously low. The storing station also provides the possibility of guiding and holding the packing units, so that they are never subject to gravity only. Thus, the reliability of the conveying process is increased. The conveying device preferably includes at least one rotor including one or more arms. Suction elements, gripping elements or similar elements are arranged at the free ends of the arms to grip packing units, to hold them, to guide them and to convey them. Such a conveying device has a substantially shorter length than, for example, a conveyor belt on which packing units are moved in cases. The short length of the conveying device also has the effect that the entire transfer apparatus is substantially shorter and more compact than it is known in the prior art. There is a plurality of possibilities of realizing the transfer apparatus, for example, with respect to how the conveying device is designed. It makes sense to use at least one rotor. The rotor may include a number of arms being used more or less at the same time during following steps in the process, and with which a number of stations can be passed through. The general design of the conveying device and the number of tracks do not depend on one another. It is clear that the conveying device has to include suction elements, gripping elements or similar elements for each track. There is a certain relationship between the number of arms of the conveying device and the number of stations to be passed. A preferred embodiment includes a rotor having three arms as conveying device, the rotor being movable to work at four different stations. Generally, there may be an additional free station or an extra station allowing for a manual insertion of packing units of desired properties into the flow of material. In case this extra supply unit is arranged in front of the storing station as seen in the conveying direction, there only has to be one single extra supply unit, no matter how many tracks the system includes.
It is generally true that the number of storing locations of the storing station is less than the number of tracks transverse to the conveying direction by 1. Thus, the lowest possible number of storing locations has to be provided, and the lowest possible number of packing units of desired properties has to be stored.
In a preferred embodiment of the system, the rotor of the conveying device includes at least three arms being equally spaced apart about the circumference of the rotor. There is a plurality of tracks. During rotation of the rotor, each arm gets in contact with the receiving station, the storing station and the stack building station. But it is also possible to vary the number of arms at the rotor. There is also a great number of possibilities of designing the gear and the transmission of the rotor.
The control device to control the movements of the storing station, the conveying device and the stack building station is designed and arranged to control the conveying device and the stack building station to either produce a completely row of packing units in each cycle of the conveying device, or not to pass on any packing units at all. If no packing units are passed on, the control device suppresses the activation of the next cycle of the stack building station. The receiving station on the one hand, and the stack building station on the other hand, are not connected by a common working or processing cycle, as this is known from the prior art, but instead, they substantially work independently. When no packing units are passed on, the cycle of the stack building station and of all following parts in the system is suppressed.
It is possible to use an extra supply unit to manually insert packing units of desired properties into the flow of material. Such an extra supply unit serves to reinsert packing units of desired properties. There only has to be one single extra supply unit no matter how many tracks of packing units are present since the extra supply unit works together with the storing station, and it may thus reach all tracks.
The detecting device to detect a packing unit of undesired properties or to detect an empty space in the plurality of tracks may watch a plurality of functions. The empty packages or the packages of undesired properties may be removed from the flow of material before they reach the receiving station, but also after they have passed the receiving station, meaning in the region of the conveying device. An ejecting device to eject empty packages and packages of undesired properties may be allocated to the conveying device. Such an ejecting station may be also arranged in the region of the rotor. Then, it is only necessary to correspondingly control the gripping elements or the suction elements. The ejection or removal of the packages of undesired properties may occur during the conveying movement from one station to another station, meaning in a middle position between two stations, for example between the receiving station and the storing station. It is also possible to separate empty packages and packages of undesired properties, for example to reuse tablets being located inside packages of undesired properties, and to reinsert the tablets into the packing operation.
Other objects, features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and the detailed description. It is intended that all such additional objects, features and advantages be included herein within the scope of the present invention, as defined by the claims.